Audio from Mail will not play on lock screen since 9.2!
This is verified from a discussion with an AppleCare specialist last night, and it's a real bummer for me and people like me who get a lot of audio attachments (mp3 etc) and need to review them on the go. Used to be (up until iOS 9.1) that if you open an audio file attachment from an email in Mail and start playing it, then lock your screen, the audio will continue play uninterrupted, and additionally you can use stop/start controls from the lock screen on that audio. Now, when you lock your screen in iOS 9.2, the audio just stops! Yay for advancement! Additionally, when you switch away from mail to say, Safari, the audio stops too. Apparently the iOS no longer recognizes Mail as a background audio source. This is a SUPER BUMMER and really needs to be fixed ASAP.
So anyway, all just to say that if you depend on this feature, please do not update to 9.2. I really wish I hadn't.
iPhone 6s, iOS 9.2